Re: [RFC v3 3/5] hid-multitouch: support for PixCir-based panels

From: Henrik Rydberg
Date: Fri Jan 07 2011 - 14:50:55 EST


On Fri, Jan 07, 2011 at 07:42:40PM +0100, Benjamin Tissoires wrote:
> Created a driver for PixCir based dual-touch panels, including the one
> in the Hanvon tablet. This is done in a code structure aimed at unifying
> support for several existing HID multitouch panels.
>
> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxx>
> Signed-off-by: Stéphane Chatty <chatty@xxxxxxx>
> ---

It looks much better now. Just a few comments and some nit-picks inline.

> drivers/hid/Kconfig | 9 +
> drivers/hid/Makefile | 1 +
> drivers/hid/hid-core.c | 2 +
> drivers/hid/hid-ids.h | 4 +
> drivers/hid/hid-multitouch.c | 468 ++++++++++++++++++++++++++++++++++++++++++
> 5 files changed, 484 insertions(+), 0 deletions(-)
> create mode 100644 drivers/hid/hid-multitouch.c
>
> diff --git a/drivers/hid/Kconfig b/drivers/hid/Kconfig
> index 401acec..511554d 100644
> --- a/drivers/hid/Kconfig
> +++ b/drivers/hid/Kconfig
> @@ -285,6 +285,15 @@ config HID_MONTEREY
> ---help---
> Support for Monterey Genius KB29E.
>
> +config HID_MULTITOUCH
> + tristate "HID Multitouch panels"
> + depends on USB_HID
> + ---help---
> + Generic support for HID multitouch panels.
> +
> + Say Y here if you have one of the following devices:
> + - PixCir touchscreen

Should also mention how to compile as module, and what the module will be called.

> +
> config HID_NTRIG
> tristate "N-Trig touch screen"
> depends on USB_HID
> diff --git a/drivers/hid/Makefile b/drivers/hid/Makefile
> index c335605..ec991d4 100644
> --- a/drivers/hid/Makefile
> +++ b/drivers/hid/Makefile
> @@ -46,6 +46,7 @@ obj-$(CONFIG_HID_MAGICMOUSE) += hid-magicmouse.o
> obj-$(CONFIG_HID_MICROSOFT) += hid-microsoft.o
> obj-$(CONFIG_HID_MONTEREY) += hid-monterey.o
> obj-$(CONFIG_HID_MOSART) += hid-mosart.o
> +obj-$(CONFIG_HID_MULTITOUCH) += hid-multitouch.o
> obj-$(CONFIG_HID_NTRIG) += hid-ntrig.o
> obj-$(CONFIG_HID_ORTEK) += hid-ortek.o
> obj-$(CONFIG_HID_PRODIKEYS) += hid-prodikeys.o
> diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
> index 88668ae..2b4d9b9 100644
> --- a/drivers/hid/hid-core.c
> +++ b/drivers/hid/hid-core.c
> @@ -1286,6 +1286,7 @@ static const struct hid_device_id hid_blacklist[] = {
> { HID_USB_DEVICE(USB_VENDOR_ID_BELKIN, USB_DEVICE_ID_FLIP_KVM) },
> { HID_USB_DEVICE(USB_VENDOR_ID_BTC, USB_DEVICE_ID_BTC_EMPREX_REMOTE) },
> { HID_USB_DEVICE(USB_VENDOR_ID_BTC, USB_DEVICE_ID_BTC_EMPREX_REMOTE_2) },
> + { HID_USB_DEVICE(USB_VENDOR_ID_CANDO, USB_DEVICE_ID_CANDO_PIXCIR_MULTI_TOUCH) },
> { HID_USB_DEVICE(USB_VENDOR_ID_CANDO, USB_DEVICE_ID_CANDO_MULTI_TOUCH) },
> { HID_USB_DEVICE(USB_VENDOR_ID_CANDO, USB_DEVICE_ID_CANDO_MULTI_TOUCH_11_6) },
> { HID_USB_DEVICE(USB_VENDOR_ID_CANDO, USB_DEVICE_ID_CANDO_MULTI_TOUCH_15_6) },
> @@ -1312,6 +1313,7 @@ static const struct hid_device_id hid_blacklist[] = {
> { HID_USB_DEVICE(USB_VENDOR_ID_GYRATION, USB_DEVICE_ID_GYRATION_REMOTE) },
> { HID_USB_DEVICE(USB_VENDOR_ID_GYRATION, USB_DEVICE_ID_GYRATION_REMOTE_2) },
> { HID_USB_DEVICE(USB_VENDOR_ID_GYRATION, USB_DEVICE_ID_GYRATION_REMOTE_3) },
> + { HID_USB_DEVICE(USB_VENDOR_ID_HANVON, USB_DEVICE_ID_HANVON_MULTITOUCH) },
> { HID_USB_DEVICE(USB_VENDOR_ID_KENSINGTON, USB_DEVICE_ID_KS_SLIMBLADE) },
> { HID_USB_DEVICE(USB_VENDOR_ID_KYE, USB_DEVICE_ID_KYE_ERGO_525V) },
> { HID_USB_DEVICE(USB_VENDOR_ID_LABTEC, USB_DEVICE_ID_LABTEC_WIRELESS_KEYBOARD) },
> diff --git a/drivers/hid/hid-ids.h b/drivers/hid/hid-ids.h
> index 0f150c7..17b444b 100644
> --- a/drivers/hid/hid-ids.h
> +++ b/drivers/hid/hid-ids.h
> @@ -134,6 +134,7 @@
> #define USB_DEVICE_ID_BTC_EMPREX_REMOTE_2 0x5577
>
> #define USB_VENDOR_ID_CANDO 0x2087
> +#define USB_DEVICE_ID_CANDO_PIXCIR_MULTI_TOUCH 0x0703
> #define USB_DEVICE_ID_CANDO_MULTI_TOUCH 0x0a01
> #define USB_DEVICE_ID_CANDO_MULTI_TOUCH_11_6 0x0b03
> #define USB_DEVICE_ID_CANDO_MULTI_TOUCH_15_6 0x0f01
> @@ -306,6 +307,9 @@
> #define USB_DEVICE_ID_HANWANG_TABLET_FIRST 0x5000
> #define USB_DEVICE_ID_HANWANG_TABLET_LAST 0x8fff
>
> +#define USB_VENDOR_ID_HANVON 0x20b3
> +#define USB_DEVICE_ID_HANVON_MULTITOUCH 0x0a18
> +
> #define USB_VENDOR_ID_HAPP 0x078b
> #define USB_DEVICE_ID_UGCI_DRIVING 0x0010
> #define USB_DEVICE_ID_UGCI_FLYING 0x0020
> diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
> new file mode 100644
> index 0000000..3b05dfe
> --- /dev/null
> +++ b/drivers/hid/hid-multitouch.c
> @@ -0,0 +1,468 @@
> +/*
> + * HID driver for multitouch panels
> + *
> + * Copyright (c) 2010-2011 Stephane Chatty <chatty@xxxxxxx>
> + * Copyright (c) 2010-2011 Benjamin Tissoires <benjamin.tissoires@xxxxxxxxx>
> + * Copyright (c) 2010-2011 Ecole Nationale de l'Aviation Civile, France
> + *
> + */
> +
> +/*
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU General Public License as published by the Free
> + * Software Foundation; either version 2 of the License, or (at your option)
> + * any later version.
> + */
> +
> +#include <linux/device.h>
> +#include <linux/hid.h>
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/usb.h>
> +#include <linux/input/mt.h>
> +#include "usbhid/usbhid.h"
> +
> +
> +MODULE_AUTHOR("Stephane Chatty <chatty@xxxxxxx>");
> +MODULE_DESCRIPTION("HID multitouch panels");
> +MODULE_LICENSE("GPL");
> +
> +#include "hid-ids.h"
> +
> +/* quirks to control the device */
> +#define MT_QUIRK_NOT_SEEN_MEANS_UP (1 << 0)
> +#define MT_QUIRK_SLOT_IS_CONTACTID (1 << 1)
> +
> +struct mt_slot {
> + __s32 x, y, p, w, h;
> + __s32 contactid; /* the device ContactID assigned to this slot */
> + bool touch_state; /* is the touch valid? */
> + bool seen_in_this_frame;/* has this slot been updated */
> +};
> +
> +struct mt_device {
> + struct mt_slot curdata; /* placeholder of incoming data */
> + struct mt_class *mtclass; /* our mt device class */
> + unsigned last_field_index; /* last field index of the report */
> + unsigned last_slot_field; /* the last field of a slot */
> + __s8 inputmode; /* InputMode HID feature, -1 if non-existent */
> + __u8 num_received; /* how many contacts we received */
> + __u8 num_expected; /* expected last contact index */

Any particular reason these are u8?

> + bool curvalid; /* is the current contact valid? */
> + struct mt_slot slots[0]; /* first slot */
> +};
> +
> +struct mt_class {
> + __s32 quirks;
> + __s32 sn_move; /* Signal/noise ratio for move events */
> + __s32 sn_pressure; /* Signal/noise ratio for pressure events */
> + __u8 maxcontacts;

Same here - its not like we allocate a million of these anyways. Simple ints should do fine.

> +};
> +
> +/* classes of device behavior */
> +#define MT_CLS_DEFAULT 0
> +#define MT_CLS_DUAL1 1
> +
> +/*
> + * these device-dependent functions determine what slot corresponds
> + * to a valid contact that was just read.
> + */
> +
> +static int slot_is_contactid(struct mt_device *td)
> +{
> + return td->curdata.contactid;
> +}
> +
> +static int find_slot_from_contactid(struct mt_device *td)
> +{
> + int i;
> + for (i = 0; i < td->mtclass->maxcontacts; ++i) {
> + if (td->slots[i].contactid == td->curdata.contactid &&
> + td->slots[i].touch_state)
> + return i;
> + }
> + for (i = 0; i < td->mtclass->maxcontacts; ++i) {
> + if (!td->slots[i].seen_in_this_frame &&
> + !td->slots[i].touch_state)
> + return i;
> + }
> + return -1;
> + /* should not occurs. If this happens that means
> + * that the device sent more touches that it says
> + * in the report descriptor. It is ignored then. */

I would put the comment above the return statement.

> +}
> +
> +struct mt_class mt_classes[] = {
> + { 0, 0, 0, 10 }, /* MT_CLS_DEFAULT */
> + { MT_QUIRK_SLOT_IS_CONTACTID, 0, 0, 2 }, /* MT_CLS_DUAL1 */
> +};
> +
> +static void mt_feature_mapping(struct hid_device *hdev, struct hid_input *hi,
> + struct hid_field *field, struct hid_usage *usage)
> +{
> + if (usage->hid == HID_DG_INPUTMODE) {
> + struct mt_device *td = hid_get_drvdata(hdev);
> + td->inputmode = field->report->id;
> + }
> +}
> +
> +static void set_abs(struct input_dev *input, unsigned int code,
> + struct hid_field *field, int snratio)
> +{
> + int fmin = field->logical_minimum;
> + int fmax = field->logical_maximum;
> + int fuzz = snratio ? (fmax - fmin) / snratio : 0;
> + input_set_abs_params(input, code, fmin, fmax, fuzz, 0);
> +}
> +
> +static int mt_input_mapping(struct hid_device *hdev, struct hid_input *hi,
> + struct hid_field *field, struct hid_usage *usage,
> + unsigned long **bit, int *max)
> +{
> + struct mt_device *td = hid_get_drvdata(hdev);
> + struct mt_class *cls = td->mtclass;
> + switch (usage->hid & HID_USAGE_PAGE) {
> +
> + case HID_UP_GENDESK:
> + switch (usage->hid) {
> + case HID_GD_X:
> + hid_map_usage(hi, usage, bit, max,
> + EV_ABS, ABS_MT_POSITION_X);
> + set_abs(hi->input, ABS_MT_POSITION_X, field,
> + cls->sn_move);
> + /* touchscreen emulation */
> + set_abs(hi->input, ABS_X, field, cls->sn_move);
> + td->last_slot_field = usage->hid;
> + return 1;
> + case HID_GD_Y:
> + hid_map_usage(hi, usage, bit, max,
> + EV_ABS, ABS_MT_POSITION_Y);
> + set_abs(hi->input, ABS_MT_POSITION_Y, field,
> + cls->sn_move);
> + /* touchscreen emulation */
> + set_abs(hi->input, ABS_Y, field, cls->sn_move);
> + td->last_slot_field = usage->hid;
> + return 1;
> + }
> + return 0;
> +
> + case HID_UP_DIGITIZER:
> + switch (usage->hid) {
> + case HID_DG_INRANGE:
> + td->last_slot_field = usage->hid;
> + return 1;
> + case HID_DG_CONFIDENCE:
> + td->last_slot_field = usage->hid;
> + return 1;
> + case HID_DG_TIPSWITCH:
> + hid_map_usage(hi, usage, bit, max, EV_KEY, BTN_TOUCH);
> + input_set_capability(hi->input, EV_KEY, BTN_TOUCH);
> + td->last_slot_field = usage->hid;
> + return 1;
> + case HID_DG_CONTACTID:
> + input_mt_init_slots(hi->input,
> + td->mtclass->maxcontacts);
> + td->last_slot_field = usage->hid;
> + return 1;
> + case HID_DG_WIDTH:
> + hid_map_usage(hi, usage, bit, max,
> + EV_ABS, ABS_MT_TOUCH_MAJOR);
> + td->last_slot_field = usage->hid;
> + return 1;
> + case HID_DG_HEIGHT:
> + hid_map_usage(hi, usage, bit, max,
> + EV_ABS, ABS_MT_TOUCH_MINOR);
> + field->logical_maximum = 1;
> + field->logical_minimum = 1;

minimum should be zero here.

> + set_abs(hi->input, ABS_MT_ORIENTATION, field, 0);
> + td->last_slot_field = usage->hid;
> + return 1;
> + case HID_DG_TIPPRESSURE:
> + hid_map_usage(hi, usage, bit, max,
> + EV_ABS, ABS_MT_PRESSURE);
> + set_abs(hi->input, ABS_MT_PRESSURE, field,
> + cls->sn_pressure);
> + /* touchscreen emulation */
> + set_abs(hi->input, ABS_PRESSURE, field,
> + cls->sn_pressure);
> + td->last_slot_field = usage->hid;
> + return 1;
> + case HID_DG_CONTACTCOUNT:
> + td->last_field_index = field->report->maxfield - 1;
> + return 1;
> + case HID_DG_CONTACTMAX:
> + /* we don't set td->last_slot_field as contactcount and
> + * contact max are global to the report */
> + return -1;
> + }
> + /* let hid-input decide for the others */
> + return 0;
> +
> + case 0xff000000:
> + /* we do not want to map these: no input-oriented meaning */
> + return -1;
> + }
> +
> + return 0;
> +}
> +
> +static int mt_input_mapped(struct hid_device *hdev, struct hid_input *hi,
> + struct hid_field *field, struct hid_usage *usage,
> + unsigned long **bit, int *max)
> +{
> + if (usage->type == EV_KEY || usage->type == EV_ABS)
> + set_bit(usage->type, hi->input->evbit);
> +
> + return -1;
> +}
> +
> +static int mt_compute_slot(struct mt_device *td)
> +{
> + struct mt_class *cls = td->mtclass;
> +
> + if (cls->quirks & MT_QUIRK_SLOT_IS_CONTACTID)
> + return slot_is_contactid(td);

No real need for a function call here...

> +
> + return find_slot_from_contactid(td);
> +}
> +
> +/*
> + * this function is called when a whole contact has been processed,
> + * so that it can assign it to a slot and store the data there
> + */
> +static void mt_complete_slot(struct mt_device *td)
> +{

Adding "td->curdata.seen_in_this_frame = true;" here...

> + if (td->curvalid) {
> + struct mt_slot *slot;

Skipping this...

> + int slotnum = mt_compute_slot(td);
> +
> + if (slotnum >= 0 && slotnum < td->mtclass->maxcontacts) {
> + slot = td->slots + slotnum;

and this...

> +
> + memcpy(slot, &(td->curdata), sizeof(struct mt_slot));

and "td->slots[slotnum] = td->curdata" here...

> + slot->seen_in_this_frame = true;

and dropping this... looks simpler, ne?

> + }
> + }
> + td->num_received++;
> +}

Writing it explicitly here so you can judge for yourself:

td->curdata.seen_in_this_frame = true;
if (td->curvalid) {
int slot = mt_compute_slot(td);

if (slot >= 0 && slot < td->mtclass->maxcontacts)
td->slots[slot] = td->curdata;
}
td->num_received++;

> +
> +
> +/*
> + * this function is called when a whole packet has been received and processed,
> + * so that it can decide what to send to the input layer.
> + */
> +static void mt_emit_event(struct mt_device *td, struct input_dev *input)
> +{
> + int i;
> +
> + for (i = 0; i < td->mtclass->maxcontacts; ++i) {
> + struct mt_slot *s = &(td->slots[i]);
> + if ((td->mtclass->quirks & MT_QUIRK_NOT_SEEN_MEANS_UP) &&
> + !s->seen_in_this_frame) {
> + /*
> + * this slot does not contain useful data,
> + * notify its closure
> + */

It does contain useful data, it is just assumed to be in the up
state. I would drop the comment and the brackets here, the quirk name
speaks for itself.

> + s->touch_state = false;
> + }
> +
> + input_mt_slot(input, i);
> + input_mt_report_slot_state(input, MT_TOOL_FINGER,
> + s->touch_state);

The values below should not be updated for an inactive slot.

> + input_event(input, EV_ABS, ABS_MT_POSITION_X, s->x);
> + input_event(input, EV_ABS, ABS_MT_POSITION_Y, s->y);
> + input_event(input, EV_ABS, ABS_MT_PRESSURE, s->p);
> + input_event(input, EV_ABS, ABS_MT_TOUCH_MAJOR, s->w);
> + input_event(input, EV_ABS, ABS_MT_TOUCH_MINOR, s->h);
> + s->seen_in_this_frame = false;
> +
> + }
> +
> + input_mt_report_pointer_emulation(input, true);
> + input_sync(input);
> + td->num_received = 0;
> +}
> +
> +
> +
> +static int mt_event(struct hid_device *hid, struct hid_field *field,
> + struct hid_usage *usage, __s32 value)
> +{
> + struct mt_device *td = hid_get_drvdata(hid);
> +
> + if (hid->claimed & HID_CLAIMED_INPUT) {
> + switch (usage->hid) {
> + case HID_DG_INRANGE:
> + break;
> + case HID_DG_TIPSWITCH:
> + td->curvalid = value;

I do not think curvalid should depend on the touch state (which is
what tipswitch is). Either move to INRANGE, or simply set to true.

> + td->curdata.touch_state = value;
> + break;
> + case HID_DG_CONFIDENCE:
> + break;
> + case HID_DG_CONTACTID:
> + td->curdata.contactid = value;
> + break;
> + case HID_DG_TIPPRESSURE:
> + td->curdata.p = value;
> + break;
> + case HID_GD_X:
> + td->curdata.x = value;
> + break;
> + case HID_GD_Y:
> + td->curdata.y = value;
> + break;
> + case HID_DG_WIDTH:
> + td->curdata.w = value;
> + break;
> + case HID_DG_HEIGHT:
> + td->curdata.h = value;
> + break;
> + case HID_DG_CONTACTCOUNT:
> + /*
> + * We must not overwrite the previous value (some
> + * devices send one sequence splitted over several
> + * messages)
> + */

How about "Includes multi-packet support where subsequent packets are sent with zero contactcount."

> + if (value)
> + td->num_expected = value - 1;

The - 1 should be dropped here.

> + break;
> +
> + default:
> + /* fallback to the generic hidinput handling */
> + return 0;
> + }
> + }
> +
> + if (usage->hid == td->last_slot_field)
> + mt_complete_slot(td);
> +
> + if (field->index == td->last_field_index
> + && td->num_received > td->num_expected)

A ">=" here.

> + mt_emit_event(td, field->hidinput->input);
> +
> + /* we have handled the hidinput part, now remains hiddev */
> + if (hid->claimed & HID_CLAIMED_HIDDEV && hid->hiddev_hid_event)
> + hid->hiddev_hid_event(hid, field, usage, value);
> +
> + return 1;
> +}
> +
> +static void mt_set_input_mode(struct hid_device *hdev)
> +{
> + struct mt_device *td = hid_get_drvdata(hdev);
> + struct hid_report *r;
> + struct hid_report_enum *re;
> +
> + if (td->inputmode < 0)
> + return;
> +
> + re = &(hdev->report_enum[HID_FEATURE_REPORT]);
> + r = re->report_id_hash[td->inputmode];
> + if (r) {
> + r->field[0]->value[0] = 0x02;
> + usbhid_submit_report(hdev, r, USB_DIR_OUT);
> + }
> +}
> +
> +static int mt_probe(struct hid_device *hdev, const struct hid_device_id *id)
> +{
> + int ret;
> + struct mt_device *td;
> + struct mt_class *mtclass = mt_classes + id->driver_data;
> +
> + /* This allows the driver to correctly support devices
> + * that emit events over several HID messages.
> + */
> + hdev->quirks |= HID_QUIRK_NO_INPUT_SYNC;
> +
> + td = kzalloc(sizeof(struct mt_device) +
> + mtclass->maxcontacts * sizeof(struct mt_slot),
> + GFP_KERNEL);
> + if (!td) {
> + dev_err(&hdev->dev, "cannot allocate multitouch data\n");
> + return -ENOMEM;
> + }
> + td->mtclass = mtclass;
> + td->inputmode = -1;
> + hid_set_drvdata(hdev, td);
> +
> + ret = hid_parse(hdev);
> + if (ret != 0)
> + goto fail;

"if (ret)" is very standard.

> +
> + ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
> + if (ret != 0)
> + goto fail;
> +
> + mt_set_input_mode(hdev);
> +
> + return 0;
> +
> +fail:
> + kfree(td);
> + return ret;
> +}
> +
> +#ifdef CONFIG_PM
> +static int mt_reset_resume(struct hid_device *hdev)
> +{
> + mt_set_input_mode(hdev);
> + return 0;
> +}
> +#endif
> +
> +static void mt_remove(struct hid_device *hdev)
> +{
> + struct mt_device *td = hid_get_drvdata(hdev);
> + hid_hw_stop(hdev);
> + kfree(td);
> + hid_set_drvdata(hdev, NULL);
> +}
> +
> +static const struct hid_device_id mt_devices[] = {
> +
> + /* PixCir-based panels */
> + { .driver_data = MT_CLS_DUAL1,
> + HID_USB_DEVICE(USB_VENDOR_ID_HANVON,
> + USB_DEVICE_ID_HANVON_MULTITOUCH) },
> + { .driver_data = MT_CLS_DUAL1,
> + HID_USB_DEVICE(USB_VENDOR_ID_CANDO,
> + USB_DEVICE_ID_CANDO_PIXCIR_MULTI_TOUCH) },
> +
> + { }
> +};
> +MODULE_DEVICE_TABLE(hid, mt_devices);
> +
> +static const struct hid_usage_id mt_grabbed_usages[] = {
> + { HID_ANY_ID, HID_ANY_ID, HID_ANY_ID },
> + { HID_ANY_ID - 1, HID_ANY_ID - 1, HID_ANY_ID - 1}
> +};
> +
> +static struct hid_driver mt_driver = {
> + .name = "hid-multitouch",
> + .id_table = mt_devices,
> + .probe = mt_probe,
> + .remove = mt_remove,
> + .input_mapping = mt_input_mapping,
> + .input_mapped = mt_input_mapped,
> + .feature_mapping = mt_feature_mapping,
> + .usage_table = mt_grabbed_usages,
> + .event = mt_event,
> +#ifdef CONFIG_PM
> + .reset_resume = mt_reset_resume,
> +#endif
> +};
> +
> +static int __init mt_init(void)
> +{
> + return hid_register_driver(&mt_driver);
> +}
> +
> +static void __exit mt_exit(void)
> +{
> + hid_unregister_driver(&mt_driver);
> +}
> +
> +module_init(mt_init);
> +module_exit(mt_exit);
> --
> 1.7.3.4
>

Thanks!
Henrik
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